1. Field of the Invention
The present invention relates to an output apparatus in which a memory of print information is provided for every color and the printing can be performed in a plurality of colors.
2. Related Background Art
Hitherto, there has been known a two-color laser beam printer of the type in which document information such as code data or the like which is sent from a host computer or the like is developed as a bit image in an internal memory and, thereafter, the bit information is read out and output as a visible image. Such a conventional printer has memories for storing a bit image to be output for every color. For instance, in the case of printing a two-color bit image (character information or image information) on one line, the bit image of the first color is first read out of the first memory and charged, exposed, and developed for a photo sensitive drum, and the bit image of the second color is then read out of the second memory and charged, exposed, and developed for the photo sensitive drum.
Therefore, the number of accessing times for the memories in the two-color laser printer is a total of four times consisting of two reading operations of the bit images and two writing operations of the bit images.
However, since those bit images are input and output by a common bus which is connected to the memories, the four memory accesses must be time sequentially executed. On the other hand, a conventional multi color printer has the problem that the timing controls for the accesses for the memories become complicated in addition to the fact that the laser exposing timings for the photo sensitive material differ with every color.
Thus, there is also the problem that a deviation of the exposing timings due to the influence of attachment errors of the laser light emitting devices used to expose the photo sensitive material is hard to compensate for by the reading timings for the memories. Further, even in the case of a printer of three colors, four colors, or the like instead of the full-color printer, there is the drawback that the above problems are enhanced.